I often see this a week or two before a shed. It's generally worse if the tank is moist, and I've started to suspect there's a little mold in there.... so I could certainly see how it could TURN into scale rot. But I pretty much only see it when an animal hasn't eaten all winter and hasn't shed in 3 months, and the scales are just old and gross and dirty and are about to come off anyway.

At this level, and right before a shed, I wouldn't worry. My animals always shed out fresh and shiny within a week of me noticing the "dirty" and "broken" scales.

But I would recommend cleaning the tank out, rinsing with 10% bleach solution, and changing the substrate after the shed.